diff -r 000000000000 -r 6474c204b198 services/common/tests/unit/test_utils_exceptionStr.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/services/common/tests/unit/test_utils_exceptionStr.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,17 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function run_test() {
+  run_next_test();
+}
+
+add_test(function test_exceptionStr_non_exceptions() {
+  do_check_eq(CommonUtils.exceptionStr(null), "null");
+  do_check_eq(CommonUtils.exceptionStr(false), "false");
+  do_check_eq(CommonUtils.exceptionStr(undefined), "undefined");
+  do_check_eq(CommonUtils.exceptionStr(12), "12 No traceback available");
+
+  run_next_test();
+});